1. Field of the Invention
The present invention relates to image acquisition devices used in optical apparatuses, such as microscopes.
This application is based on Japanese Patent Application No. 2011-119405, the content of which is incorporated herein by reference.
2. Description of Related Art
In microscope observation, high-resolution images are required when performing pathological diagnosis based on the condition of cells or when acquiring images for detecting changes in a sample based on weak fluorescence. As means used for acquiring images, image acquisition devices employing image acquisition elements, such as CCDs, have been used in place of image acquisition devices employing conventional silver-salt films as image acquisition media (for example, see the United States Patent Application, Publication No. 2003/0117523 A1, Japanese Unexamined Patent Application, Publication No. 2007-208614, and Japanese Unexamined Patent Application, Publication No. Hei 9-186917).
An image acquisition device disclosed in the United States Patent Application, Publication No. 2003/0117523 A1 includes a solid-state image acquisition element for acquiring an image of an object, solid-state-image-acquisition-element cooling means for cooling the solid-state image acquisition element, and a printed board for electrical signal wiring. The printed board for electrical signal wiring serves as a portion of sealing means for sealing the solid-state image acquisition element and the solid-state-image-acquisition-element cooling means.
In an image acquisition device disclosed in Japanese Unexamined Patent Application, Publication No. 2007-208614, a partition wall divides the interior of the image acquisition device into a first chamber having an image acquisition element disposed therein and a second chamber having an opening. The first chamber and the second chamber are thermally connected to each other via a heat transfer member having thermal conductivity higher than that of a camera body.
An image acquisition device disclosed in Japanese Unexamined Patent Application, Publication No. Hei 9-186917 includes a plurality of image acquisition elements inside the image acquisition device, and optical-path splitting means for splitting an optical path extending from an objective lens to the image acquisition elements so as to guide light to the respective image acquisition elements. In this image acquisition device, lenses having different focal lengths are provided in the optical paths extending from the optical-path splitting means to the image acquisition elements so as to vary the magnification of images formed on light receiving surfaces of the image acquisition elements.
Color reproducibility is an important requirement in image acquisition elements used for pathological diagnosis. On the other hand, sensitivity is an important requirement when observing weak light, such as fluorescence or luminescence. Accordingly, the desired characteristics of image acquisition elements vary depending on the observation methods. By disposing image acquisition elements having different characteristics within an image acquisition device, a single image acquisition device can be used for various purposes.
When weak light is to be detected using an image acquisition device having two image acquisition elements disposed therein for such purposes, it is desired that observation light be made to enter only the image acquisition element that is to be used for image acquisition. Therefore, a driving mechanism is necessary for moving the optical-path splitting means that splits the optical path extending to the image acquisition elements. The driving mechanism uses mechanism components, such as gears or a guide mechanism. However, such a driving mechanism becomes abraded with use, thus producing dust particles, such as metal particles.
The image acquisition device is provided with a sealing section for preventing condensation, which is formed due to a change in outside temperature or due to cooling of the image acquisition elements, from adhering to the image acquisition elements or to glass cover members for the image acquisition elements, the aforementioned optical-path splitting means, and a connection section for connecting to a microscope. Since these components are disposed in the observation light path, the aforementioned dust particles would be reflected in the image of the object if they adhere to the components.